His mother Suzanne, 35, rang an ambulance when he started vomiting and rolling around in pain.

Liam, who had no underlying conditions which could have contributed to the tragedy, died four days later in hospital.

His seizure may have been caused by pressure build up in the brain due to the powerful sneezes, although such cases are extremely rare.

Suzanne, of Stockton-on-Tees, told how her son came downstairs complaining of a headache, saying he had just sneezed six times in a row.

She said: “I thought it was nothing serious at first and I told him I would get him some paracetamol but then he got poorly very quickly.

Initially he was saying “my head hurts, my head hurts”, then he started being sick. His eyes were going back and forward and he was rolling around in pain.

“He couldn’t work his hands. I gave him a glass of water but he threw it over himself as he was so hot. He was so hot, I couldn’t touch him, then he started to fit. I rang an ambulance and they were here within minutes.”

Liam was rushed to the emergency department of University Hospital of North Tees before being transferred to the James Cook University Hospital in Middlesbrough.

He had surgery to remove a clot on his brain and spent four days in critical condition in intensive care. His mother faced an anxious wait for news.

“I felt numb, shocked and empty,” she recalled yesterday (Fri). “I was just watching the clock ticking. I could not think of anybody else but Liam.”

Liam eventually died on his younger brother’s 12th birthday. Suzanne said: “I never would have imagined that something as simple as a few sneezes could kill a healthy young boy. There was nothing to indicate

that something like this would happen. I couldn’t believe it. I asked for a specialised post mortem and it came back that he was absolutely fine.

“It is usually more common for this kind of thing to happen in people over the age of 40, not in someone so young and fit. I don’t think there was anything anybody could have done to save Liam. It could have

happened at any time or any day. I am just thankful that I was there to try and help and he wasn’t by himself.”

Since his death nine months ago, Liam’s heart, liver, pancreas and kidneys have been donated to help save the lives of six other people.

Suzanne, mum to Amy, 17, Elliott, 12, Erin, nine, Lewis, three, and Evie, one, has drawn comfort from the fact her son saved so many

lives. Funds were also raised at his funeral for Education Centre for Children with Down’s syndrome (ECCDS) - a charity which helps his brother Elliott, who has Down’s syndrome.

She added: “Of course I am amazingly proud of Liam for making the decision to become an organ donor. Just six months before his death Liam was telling me you should be prepared to donate organs if you are

willing to receive, then six months later we were fulfilling his wishes.

“Liam was very sensitive and loving, he was a real character. I could have mature conversations with him but he was still young and liked to get himself into mischief.

“I would never have swapped him for the world.”

The funeral collection raised more than £500 and the charity paid tribute by presenting a series of prizes in his honour at its annual World Down’s Syndrome Awareness Day celebration.

People can die from a sneeze which triggers a pre-existing condition - such as a blood clot or a fracture. They can also die from the pressure that builds up in the brain, with no pre-existing conditions, although experts describe that as very rare.